Control system for compressors and the like



B. S. AIKMAN.

CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

'APPLICATION FILED MAY 21. 1917.

Patented Dec.13, 1921.

14 SHEETS-SHEET I.

B. s. AIKMAN.

CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

APPLICATION FILED MAY 21. I917- 1,400,133. Patented Dec.13, 1921.

I4 SHEETS-SHEET 2.

B. S. AIKMAN. CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

APPLICATION FILED MAYZI I917- Patented Dec. 13, 1921.

' 14 SHEETS-SHEET 3.

B. S. AIKMAN.

CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

' APPLICATION FILED MAYZI, 1917. 1 ,400, 1 Patented D60. 13, 1921.

14 swans-sneer 4.

.DII II] B. S. AIKMAN.

CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

APPLICATION FILED MAY 21, I917- Patented Dec. 13, 1921.

14 SHEETS-SHEET 5.

ZZZaierInZeZ B. s. AIKMAN.

Patented Dec. 13, 1921.

14 SHEETS-SHEET 6.

124 v A 110 10 Imam APPLICATION FILED MAY 21-, I911- CONTROL SYSTEM FQR COMPRESSORS AND THE Ll-KE. 1,400,133.

B. s AIKMAN.

CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

APPLICATION FILED MAYZI, 19]]- 1,400,133.

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T: mm own m 8H m B. s. AIK MAN. CONTROL SYSTEM FO R COMPRESSORS AND THE LIKE.

APPLICATION FILED MAY 2|; l9]?- Patented D00. 13"," 1-9 21.

14 SHEETS-SHEET 8- B. S. AIKMAN.

CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

. APPLICATION FIL'ED MAY 21, 1911- 1,400,133. Patented Dec. 13, 1921.

B. s. AIKMAN.

- CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

APPLICATION FILED MAY 21. 1917. Patented Dec. 13, 1921,

I4 SHEETS-SHEET Iln m. K n Ti Q i l l l I l l I I l 6 8 a 3.4 I B n I n E J 5 w. w

B. S. AIKMAN. CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

APPLICATION FILED MAY 21, I917- Patented Dec. 13, 1921.

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B. S. AIKMAN.

CONTROL SYSTEM FOR COMPRESSORS AND THE LIKE.

AP PLICATION FILED MAY 21. I917- Patented Dec. 13, 1921.

14 SHEETS-SHEET l3.

U m .mv wwwww 811 B. S. A!KMAN.' CONTROL SYSTEM FOR COMPBESSORS AND THE LIKE.

APPLICATION 1150 MAY 21, 1917.

- Patented Dec. 13, 1921.

14 SHEETS-SHEET 1 4.

9% Fan Qhh .w 1 I QG m NITED S T-AT ESa PAT EjNT' OFFICE.

I BURTON S. AIRMAN, OI MILWAUKEE, WISCONSIN, ASSIGNOB 'I'O NATIONAL BRAKE &

ELECTRIC COMPANY, 01 MILWAUKEE, WISCONSIN, A CORPORATION 01' WISCONSIN.

eomaor. srsrruiproa, conrimssons AND m LIKE.

To all whom it may concern:

Be it known that I, BURTON S. AI/KMAN, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented a certain new and useful Improvement in Control System's for Compressors and the like, of. which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, formin a part of this specification.

y invention relates to a system of control for air compressors and the like.

Due to the simplicity, safetyand adaptability of compressed air it has come into very general use. It is particularly desirable for operating certain types of intermittently active apparatus which of necessity must be isolated and subject to infrequent attention or inspection. L

Railway switching and interlocking plants, pumping plants and the like are instances of such installations.

The reliability :of compressed air as an operating medium recommends it for some types of installation. To keep the over-all reliability of the plant'at a maximum it is necessary to safe-guard the compressor and particularly the electric motor and other electrical equipment. It isxbetter to prevent the motor an compressor from being started than to allow the same to start and 'to be damaged. The plant can be operated for a time on the air in the main reservoir even at reduced pressure while attention is given to the motor and the condition or obstruct1on removed.

My invention aims primarily toprovide a starting and control system for motor driven compressors which controls automatic stopping and startin of the motor and loading and unloadin 0% the compressor and whic is particular y characterized by provision for safe-guarding the electrical apparatus as well as the compressor itself against damage. There are two pieces of electrical appa ratus which are to be protected, namely the motorand the starting resistance. Antomatic electrical protection of these pleces would e tail expensive apparatus too complicatedand delicate for the attendants to Specification of Letters Patent. Paten ed 1) c 1 1917. Serial No. 189,997.

Application filed Kay 21,

circuit to the'power main, with a suitable starting resistance in circuit either in the primary or secondary of the motor. This mam switch is overned by an operating element which he ds the switch closed for a predetermined time'to start the.motor. If some condition exists which would revent the motor from starting and picking up speed such for instance asan open phase on a polyphase circuit, excessive inechanical friction, improper voltage or frequency, excessive load open secondary or any of the thmgs which might occur, and the motor does notcome up to speed in a predetermined time the main switch automatically opens. This is necessary because the starting resistance is not designed for continuous operation and if it is left in the circuit too long itwill be overheated and damaged.

I provide a cut-out switch for the starting resistance and an operating element for the switch which depends upon the motor coming up to speed. For this purpose I employ a hydraulic system having a raduated orifice governing the escape of t e liquid from the system at a predetermined rate and a pump operated in unison with the motor shaft for pumpin liquid into the system in accordance wit the speed of the motor. If the motor speeds up properly and exceeds a certain critical speed pressure accumulates in the hydraulic system andoperates the cut-out switch. Operation of the cut-out switch locks the main switch in closed position. pressure by the motor coming up to full speed operates a pressure controlled element that loads the compressor.

Further accumulation of This hydraulic system becomes the controlling means for the motorand the compressor and continued operation of the mo- 1 once causes unloading of the compressor opening of the starting cut-out switch and opening of the main switch in turn.

Upon lowering of the air pressure in the main reservoir the governor operates to initiate another starting and loading of the 'com ressor for replenishing the air supply as .a ove outlined.

Suitable apparatus may be employed for opening the hydraulic system upon the occurence of any electrical or mechanical conditiions that may be dangerous or undesira e.

This provides a control system which is more flexible and reliable than a system of fuses overload switch or the like, although.

an automatic pumping plant or system and hence my invention has other more specific objects.

. As an example of such further object it is the aim of my invention to put the pump and the starter system under the control of the lubricating system. A further aim of the invention is to provide improved means for controlling the system for cooling the compressor. Another aim is the provision of an improved blow-out for the main switch. A further aim is the provision of over-load control means for the system. Numerous aims and objects will be apparent from the following specification.

In' the accompanying drawings which form a part of the present specification I have illustrated one embodiment in which my invention may appear.

' Figure 1 is a side elevation of a compressor and the operating and control mechanism therefor;

Fig. 2 is a rear end elevation of the same; Fig. 3 is a bottom plan view of the switch board showing .the main switch starting re- 'sistance switch and starting resistances;

Figs. 4, 5, 6, and 7 are parts of a comprehensive diagram showing diagrammatically the connection and operative relation of the various parts. Y (Figs. 4c 5 and 6 are to be laid beside each other from left to right and Fig. 7 is to be laid below Fig. 4.) Fig. 4 shows in elevation the main switch and the starting resistance switch with the 60 elements for operating the same;

Fig. 5 shows the pressuregovernor, the

cooling water control and the suction valve control; f

Fig. 6 shows the operating element for disabling the suction valve;

Fig. 7 shows the pump and connections in N the motor base;

Fig. 8 is a view similar to Fig. 5, showing the governor in running position;

Fig. 9 is a section of the valveunloading cylinder when the same is in the starting position;

Fig. 10 is a view of the same in running position;

Fig. 11 is a right side elevation section of the main switch;

Fig. 12 is a left side elevation partly in section of the starting resistance switch;

Fi 13 is a rear elevation of the switch boar showing the motor starting resistances and the connections; I i

Fig. 14 is a diagramof the electric circuit emplo ing an overload protectivedevice for unloa ing the compressor when the,.load upon the motor is excessive; and .1.

Fig. 15 is a diagram of the circuit connecpartly in tions without said protective device.

Fig. 16 is a diagram of a modified form of pressure controlling means; and

Fig. 17 is a plan View of the governor employed in the modification.

In carrying out my invention I have made use of the following general instrumentalities.

I employ a pressure controlled governor subject to the air pressure for initiating the necessar starting and stopping actions for cutting 1n and out the action of the driv ng motor and for initiating the steps of loadlng and unloading the compressor.

I employ a hydraulic pressure system for operating a switch which brings the motor up to speed, for loading the compressor and for controlling thefiow of cooling water to the compressor jacket. This hydraulic sysan operating medium, thus further safe-' guarding the mechanism.

' line or overload on the motor should occur.

The compressor 1 and motor 2 are mounted upon a common base 3. This base provides a pedestal 4 for the motor 2. The motor has a driving shaft 5 bearing a pinion 6 meshing with the gear 7 which gear is mounted on the end of the crank shaft 8 of the compressor. The base 3 supports a housing or crank casing 9 for inclosing the crank shaft and the gears and this housing is made tight to provide a suitable bath of oil for lubricating the gears, the crank-shaft and crank-pin, bearings, the pistons and cylinders and other bearings. Each side of the crank casing is accessible through the removable plates 10 tem employs the oil used for lubrication as I necessary feed wires through the main circuit controlling switch 17. The secondary leads 18 which connect with the rotor pass in through a suitable conduit entering the rear of the base at 20 and emerging from the.

front of the base at 21 from whence these leads emerge and are connected to the starting resistances 22, 23 and 24 WhlCh are mounted upon the back of the switch board '25. This switch board is mounted upon the compressor base 9 at the front of the same in a vertical position. A suitable short circuiting switch 26 for short-circuiting the secondary resistances is mounted upon the front tion stroke. The'spring 28 engages the upper end of the stem 29 and ten of the switch-board 25 close to the main circuit controlling switch 17.

Each compressor cylinder is provided with one or more suction valves 27 that are normally held closed by means of springs 28 except when they are open during the sucs to hold the valve 27 against its seat. Above the stem 29 I and preferably axially in line with the same is provided a thrust rod or unloading rod 30 for each valve. The rod 30 passes through.

a bushing 31 which is mounted in the upper part of the hollow cylinder head 32 and is normally held in raised position by means of the spring 33 while the compressor is in the operating condition. A shaft 34 is ivoted slightly above the compressor cylin. er and upon this shaft are clamped o erating arms 35 bearing adjustable spring p ungers 36 in a casing 37 at the outer end of the same for holdingthe suction valve 27 0 "en for unloading the compressor. Each 0 the. operating arms 35 by means of its yielding spring plunger 36 is able to unload the coiiperating' valve at the time that that valve is drawn down by the suction stroke of the corres onding piston. This is fully described in t e coendin ap lication of W. I.- Richards, erial um r 804,958, now Patent Number 1,230,925. A single unloading arm 38 is connected to'the unloading shaft 34 and serves to operate simultaneously all 'of the arms 35.

At the rear of the compressor is mounted a valve 39 controlling the admission of cooling water from the water inlet'40 to .the

' .jacket of the compressor cylinders.

. .A pressure controlled governor 41 which is rovided with an auxiliary a r reservoir 42 is also mounted upon the rear of the compressor (see Fig. 5). The governor 41 is connected by the necessary pipes to the various ppe'rating elements as will be described ater.

A tank or reservoir 43 is connected tothe discharge main of the compressor, which is not shown in the drawings, and is also connected by a pipe 44 through'a cook 45 and a strainer 46 to the governor 41.

Within the crank case and connected to the end of the shaft 8 I have provided a small oil pum 47 which has an eccentric 48 connected to t e end of the shaft 8. A small well 49 is formed near the end ofthe crank case and the ump 47 is lowered into the same and held upon the base 3 by means of suitable lugs50 on the frame of the pump 47. As above explained the crank case contains a bath of oil and this oil flows into the well '49 through an opening 51. The oil is introduced through a pipe 52 the upper end of which is covered by the screw cap 53. A gage glass 54 is connected by means of a short'piece of pipe 55 and a T' 56 to the pipe 52so that the gage glass 54 isin communication with the oil .in the crank case. To fill the case the cap is unscrewed and oil is poured into the pipe 52 until the levelof the same is brought to substantially the top of the ipe 52 as is shown by the dotted line 57. Wlien the compressor is running the oil level drops to substantially the line 58 inasmuch as some of the oil is taken up by the pump and is distributed throughout the systern, as will be explained later, and in view of the fact that some of the oil is s lashed up and is running down the side wa ls and the like. The line 59 represents the danger level when the oil drops below the intake 60 of the pump 47 Having now designated the main pieces or groups of apparatus I shall proceed to a detailed description of the various pieces. of-

apparatus or groups of elements starting with the hydraulic oil system for operating the unloader and the starting resistance switch.

Hydraulic system for pperatingrhe loader and starting remtance switch.

The pump 47 has a suitable operatingpis-.

ton 61 connected by the rod 62 to the eccentric 48 which is mounted upon the end of the compressor shaft 8 and which is driven in therethrough is connected in. the hydrau 1c main '66 'at any convenient int w discharge from the orifice wi l flow back into the crank-case. The pipe 69 connected-to'an ere, the

opening in the wall 70 of the crank case housing communicates through a separable fitting 71 to the hydraulic inlet port 72 of the switch-operating cylinder 73 'for the Starting resistance switch 26. The cylinder 73 is removably mounted upon the face of v contacts 80 and 81, thus placing the motor 2 v20 directly across the power leads or full speed, full load operation. The cylinder 73 is provided with a separable head 82 bearing a relief valve 83 which normally closes a port 84' of suflicient size and capacity to relieve the pressure of oil within the cylinder when the valve is opened but not so great as to drain the cylinder at once. The valve 83 has a stem 85 which is connected to a plunger 86 restin upon a flexible diaphragm 87 which is held in place by a recessed plug 88, the recess or chamber 89 of .WlllChlS connected to a pi e. 90 that connects the recess or chamber to t e auxiliary air reservoir 42. A spring 91 normally ho ds the valve 83 upon its seat so that oil pumped into the cylinder 73 tends to raise the piston 77. The chamber 92 which is formed below the valve ,83 and above the diaphragm 87 is connected by a separable pipe 93 to an opening 94 in the top of the crank case 9. Thus oil that is discharged through the valve port 84 is returned to the interior of the crank case. The piston 77 when it is at the top of its stroke rests against a shoulder formed at the upper end of the cylinder bore so that the pressure of the fluid upon the piston 77 is mainly taken up at this point and does not injure the contacts 201 and 244. Any of the oil which leaks past the iston 77 passes out the overflowv330 throug the passage 329 and back to'the crank case. This assageway at the same time permits of rapid return of the piston 77 since some of the oil in passing out of the exhaust port 84 will be projected through the passageway 329 and overflow 330 back intothe cylinder on top of the piston 77.

The hydraulic main 66 is connected by a pipe 95 tothe unloading cylinder 96 for unloading the valves of the compressor. The cylinder 96 is in fact a compound cylinder comprisingthe main bore 97 within which plays the piston 98, this piston being connected by a stem 99 to a piston rod100. The upper end of the piston rod 100 passes through the end of the-operating arm 38 as is shown at 101'having a collar 102 adapted to bear upon the end 101. The upper end of the cylinder 96 is covered by a housing .103 which incloses a relatively stifi' spring 104, this spring being compressed between the u per end'of the piston stem 99 and the top 0? the housing 103 so as to pull the rod 100 and the unloading arm 38 down. The function of this s ring is to unload the compressor except when suitable fluid pressure is maintained within the cylinder bore 97.

Adjacent its upper end the cylinder bore 97 is provided with an escapement or release port 105 which is adapted to be uncovered iston 98 is moved to 1tsupperwhen the most positlon. The escapement or release port 105 communicates by means of a passage 106 with an opening 107 in the top of the crank chamber 108 upon'which the cylinder 96 is mounted. The lower end of the cylinder 96 projects down into the crank case and vis closed off by the cylinder head 109 which contains a valve port 110 nor mally closed by a valve 111. The cylinder 96 is provided with a liner or auxiliary cyl-.

inder 112 mounted upon the inside of the head 109 axially in. line with the bore 97 The cylinder 96 is counterbored as is shown at 113 to provide a passageway around the outside of the auxiliary cylinder 112, this passageway 113 being in communication with the pipe 95 and communicating with the interior of the auxiliary cylinder 112 through three sets of ports, namely the ports 114 'adjacentthe cylinder head 109 at the lower end of the auxiliary cylinder 112, the

ports 115 at the opposite endof the cylinder 112, and the intermediate ports 116.

The auxiliary cylinder 112 is provided with two pistons 117 and 118, slidab-le within the bore of the c linder. The valve 111 has a stem 119 which is connected to the lower piston 118. A spring 120,surroundsv the valve stem 119 and tends to force the piston 118 upward thereby holding the valve lll'over the port 110 in closed position. When the piston 118'is moved to its uppermost position as is shownin Fig. 9'

this piston covers and closes ofi' theports 116 in the side walls of the cylinder 112. The lower piston 118 is provided with a stem 121. which projects upwardly and serves as a guide for aspring 122 which bears against the lower. side of the upper piston 117 tending to separate the pistons 117 and 118. A valve port 123 through the piston 117 is closed off by the projectingstein 124 secured to the piston 98 that moves in the main bore 97 when the mechanism is at rest. I

Asoil is pumped into the hydraulic main 66 when the motor is first started, a certain part of the same escapes through the graduated orifice 68, the remainder passing throughthe pipes 69 'and 95 to the switch operating and the compressor loadingcylinders 73 and 96 respectively.

A' certain relation exists between .the

starting switch operating cylinder and the unloader operating cylinder which is essential to the proper operation of the deviceand for the purpose of bringingLout thisrelation I shall now describe the operation of.

this much of the machine.

Operation of the starting resistance switch,

controlh'ng mechanism and 0f the un- Zoadcr mechanism.

The proportion of the spring strength for .the switch operating cylinder with respect I .suflicient to move the piston 77 against the spring 76 will be insufficient to move the piston 98 against the spring 104. As oil is forced into the main 66 by operation of the pump 47 and as the speed of the driving motor'i'ncreases the oil ressure in the main 66 and connected con uits will rise until such a pressure is obtained where the piston 77 begins to move upward and finally this piston is moved, upward to such an extent that the switch contacts 78 and 79 will be brought against the stationary contacts 80 and .81 and the starting resistance cut out of the circuit. It can be seen that a predetermined speed, is necessary before the short circuiting switch will be operated because of the escapement of pressure through the graduated orifice 68. As thespeed of the motor increases after cutting out the starting resistance the pressure will rise higher in the systemand at full speed will reach a pressure sufiicient to move the piston 98 agalnst the spring plained the spring 104 normally holds the operatmg arm 38 of the unloading device 1n its lower o'sition so that the suction valve 27 is held 0 of its seat. The' oil under pressure enters through the pipe "95 into the counterbore 113v and from there passes through the upper port 115 toflthe interior of the auxiliary cylinder 112 forcing the piston 98 upward. As the piston 98v rises .the projecting stem 124 uncovers the port 123 in the top of the upper auxiliary piston filling the space between the-two auxlliar. pistons 117 and 118 with oil thus equa izing the fluid ressure upon both sides of the piston 117. Kt the same time oil enters the bottom of the auxiliary cylinder through the lower ports 114 thereby equaliz ing the pressures upon both sides ofthe lower auxiliary piston 118 and hence the into the cylinder will escape into the pas- .the compressords running the 104. As previously ex -tons are free to operate, the first mentioned spring 120 serving to keep the valve 111 closed-and the second spri 122 tending to cause the upper auxiliary piston 117 to rise in the cylinder 112.

When the main piston 98 has been forced up to the point where it uncovers the relief port 105 any further oil which is pumped sage 106 through the passage 107 back to the crank case. When the piston 98 is in the position described'the operating arm 38 will have been permitted under the influence of the springs 33 to be raised to such a position that the suction valves 27 are free to function in their usual manner.

As will be seen from Fig. 5 after the unloading mechanism has been operated to put the suction valves in operating position and iston 98 remains at a distance above t e upper auxiliary iston 117 in the position de-. termined By the port 105. The auxiliary piston 117 has been'raised by its spring 122 into the position shown in this figure and the s ace between the upper auxiliary piston 11 and the lower auxiliary piston 118 is filled with the liquid under pressure.

Raising the operating arm 38 of the unloadin mechanism serves to open the valve 39 WlllCl'l is connected in the cooling water system. An adjustable arm 125 is mounted upon the unloading shaft 34 and carries at its outer end 126 an adjustable spring plunger 127 which bears against the valve operating rod 128 provided at its outer end with a piston member 129. The piston member 129 bears against adiaphragm 130 which closes off one side of the valve body 131. A valve member 132 is guided to cover and un-' cover the ports 133 when the operating rod .128 is moved in or out. The valve body 131 has an outlet port communicating with the r pipe 134 that leads to the cooling jacket of the cylinders. It can be seen that as the op- 1 erating arm 38 of the unloading mechanism is raised by the springs 33 the valvemember 1 132 will be released from the seat at the port 133 and the pressure of'the water will open the valve and permit the cooling water to flow through the cylinders. The valve member 39 permits cooling water to enter the jacket as'long as the'unloa ding device permlts the valve 27 to function.

Assume that the operation of the com- "tions of the spring strength of the cylinders .73 and 96 flows into the chamber 89 raisingthe dialp lliragm 87 thereby opening the valve 83.

- ual and the first consequence of the same is that-the spring 104 begins to force the piston 98 of the unloading cylinder downward. The piston 98 will oscillate slightly with the strokes of the pump 47 but as the 011 escapes through the port 84 the stem 124 of the pis- "ton 98 will finally strike the top ofthe aux iliary piston 117 thus closing off the port 123 1n the top of that piston, trapping the oil between the upper piston 117 and the lower piston 118 and as the pressure is further reduced the spring 104 will exert ts pressure against the upper piston 117 and the piston 117 in turn transmits. the pressure to the lower piston 118 through the medium of the trapped 'oilbetween thesevparts thus forcing the lower piston 118 downward and opening the valve 111 thereby permitting the oil within the cyllnder 96 to escape rapidly through the ports 114 and through theport 110. As the lower piston 118 is thrust downward it uncovers in Fig. 9.

i and connected theintermediateports 116 and permits the oil to escape from between the two pistons and finally permits the valve 111 to close and the parts to .assume the position shown After the unloading mechanism has thus been operated tounload the valves 27 the pressure of the oil ,in the hydraulic main parts will drop "to such a'.

point that the sprin 76. of the switch operating cylinder 73 wi l overcomethe oil pres sure and the starting resistance short cir: cuiting switch will be opened. As the piston rod 75 drops downward it trips out the emain switch 17 by before the switch is means of a mechanical release as will be described later.

It will be noted that due to the propor the starting resistance'will be short circuited before the compressor is loaded and the compressor will be unloaded opened. The operation of the hydraulic system in connection with the stopping and starting mechanism has been set forth sufiiciently so that certain advantages of this type .of control and ofthe particular combination of elements is now apparent. If through an or a gradual "using up of the oil compressor it should occur that the .oil should drop down'to'the danger level-represented by the line 59 the compressorcould not be loaded. This Is apparent because the pump would be unable. to draw oil'after the level of the oil fell below thesuction intake 60. There might be'sufiicient upon the hydraulic system I shall now-'descr present system. Any oil toclosjthe m resistance short circuiting switch 26 but in tion in pressure in' the hydraulic main-is that the spring 104 begins toforce the piston 98 of the unloading cylinder downward causing the piston 98 to strike the auxiliary piston 117 and, as hereinabove described, force the valve 111 oifof its seat and open the port 110. Before the valve lllhas been again seated sufficient oil-has escaped from the hydraulic main to eifect the opening of the main switch. However the machinery will not be running dry when the oil has reached the danger level as there is still ample to protect the maehineryfagainst damage. he 0 erator or attendant is warned of the an er by opening of the main switch and re sal of the compressor to start'automatically. Inspection of the age-glass 54 will reveal the cause of the i culty. If any rupture of the oil conveying -ipe or of the oil containin chamber shou d'occur or in the event that t e machine is not running at proper speed the same' condition "of controlklwill prevail.

operating cylinder 0 oil the main switch will automaticall open within a very short time after it. is -c sed by leakage of the air from the auxiliar reservoiras will be .described later. T e hydraulic system and connected parts is primarily a protecting system. I the motor does not come up to speed thepump will fail. to accumulate pressure due to the escapement of oil out of the graduated orificel The starting resistance cut-out switch will not close and as a consequence the main switch will open. The speed at which the system accumulates pressure may be nicely predetermined by adjustment of the size of the-orifice. An condition electrical or mechanical whi would prevent the motor from properly starting or runningat full speed will. act and it in turn willprotect the apparatus.

ibe the operation of the automatic governor '41. system inthe t a z'r governor.

. The automatic air governor 41 isof a type heretoforeknown and will not be descri ed. in detail except where the same is necessary If the loss of oil is suificie t to rob theswitch to' set ou'tthe'function of theysame in the I other form of go'v-- ernor K111011115 capab e of closing the main switch when the pressure in the main reser 

